Rotary engines, such as for example Wankel engines, use the eccentric rotation of a piston to convert pressure into a rotating motion, instead of using reciprocating pistons. In these engines, the rotor includes a number of apex or seal portions which remain in contact with a peripheral wall of the rotor cavity of the engine throughout the rotational motion of the rotor to create a plurality of rotating cavities when the rotor rotates.
In Wankel engines, the inlet and exhaust ports are usually designed mechanically to allow a minimum overlap between them during the intake and exhaust portions of the cycle, such as to purge the exhaust cavity of combustion gases prior to re-filling the intake cavity with a fresh supply of air. Failure to purge the exhaust cavity of the combustion gases may result in a reduction in cycle volumetric efficiency. However, overlap of the ports may limit the range of volumetric compression ratio that can be obtained. Therefore, there remains a need for improvement in optimizing how rotary engines may be operated.